1. Field of the Invention
The present invention relates to an illuminating device and a plant growth regulation method using the same.
2. Description of the Related Art
Conventionally, in a plant factory which is a system for planned production of plants in a closed or a semi-closed space having a controlled internal environment, the growth is regulated by adjusting the temperature, fertilizers, time of light irradiation, illuminance, and the like.
In recent years, there has been a report regarding a method for promoting raising of plants by means of regulating the quality of light in such a plant factory (see JP2007-222039A). Moreover, a plant growth regulation method by the irradiation of polarized light has been proposed (see JP2008-228688A, JP1990-283217A (JP-H02-283217A), and JP1990-283218A (JP-H02-283218A)).
However, in the illuminating devices described in JP2007-222039A, JP2008-228688A, JP1990-283217A (JP-H02-283217A), and JP1990-283218A (JP-H02-283218A), a large number of members for regulating polarization state are required, and this leads to a problem that the cost of the device increases. In addition, an illuminating device that can irradiate light having natural color shades uses a large number of light sources for light irradiation, and this leads to a problem that energy efficiency becomes poor.
The present invention has been made in consideration of the above circumstances, and aims to solve the various conventional problems described above and achieve the following objects. That is, an object of the present invention is to provide an illuminating device that makes it possible to reduce the number of members for regulating a polarization state and can irradiate light having natural color shades without decreasing energy efficiency of light irradiation, and a plant growth regulation method using the illuminating device.